🚀 go-pugleaf

sl@wimsey.bc.ca (Stuart Lynne) writes:

>In article <1g4h48EINNt1v@uni-erlangen.de> mskuhn@immd4.informatik.uni-erlangen.de writes:
>>bakker@cs.rulimburg.nl (Harm Bakker) writes:
>>
>>  rare escape sequences, ...). Messages are streams of bytes delimited by
>>  length indicators, the easiest, most efficient and most robust
>>  method possible.

>Not too quible too much. But I'd hesitate to say that it's the easiest. 

>If a data producer must know exactly how much data he's going to produce
>he will have to buffer it before sending so he can count it. If you have a
>method of indicating end of data you can simply send it as you produce it.

But ASN.1/BER offers you exactly this facility: If you you have
a data type OctettString (a 100% transparent byte stream) with a value
of length 30 MB, then you can split the OctettString in a sequence of
blocks of manageable size (manageable for the sender, receiving is simpler)
and each block is delimited by a length indicator. After the final block
you send a block with the length indicator 0 and the whole value
is delimited. This facility has been part of the BER encoding of ASN.1 for
nearly 10 years now (if we go back to the early X.409 version).

So I don't understand your problem. Tell me a more efficient solution,
that avoids parsing the input stream for escape sequences and
meta-escape sequences that hide escape sequences in the data stream
(e.g. if you mail a document that describes that !@! is the delimiter
of a message, then you have to convert !@! in something less dangerous
[byte stuffing]). This costs a lot of CPU cycles if you have to look at
each of millions of multi-media bytes in your parser. Using X.400, you
can tell the DMA to transfer manageable blocks in BER encoded messages
quickly to the MPEG audio/video decompression chip. :-)

Markus

-- 
Markus Kuhn, Computer Science student -=-=- University of Erlangen, Germany
Internet: mskuhn@immd4.informatik.uni-erlangen.de  |  X.500 entry available
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